Heating system



May 13, 1941. F. A. FURLONG HEATING SYSTEM Filed Dec. 25, 1938 2 Sheets-Sheet 1 Inventor fiancrls orneys y 1941- F. A. FURLONG 2,241,661

HEATING SYSTEM Filed Dec. 23, 1958 2 Sheets-Sheet 2 IEITI 5.. 11W) will! Inventor FPwnc/ls /4. far/027g Patented May 13,1941

HEATING SYSTEM Francis A. Furlong, Chicago, Ill., assignor to Autogas Corporation, Chicago, 111., a corporation Illinois Application December 23, 1938, Serial No. 247,352

18 Claim.

This invention relates to heating systems and more particularly to systems for extracting heat from flue gases and to safety controls therefor.

One of the objects of the invention is to provide a heating system in which the latent heat in the furnace or other burner is retrieved when the furnace is out of operation. According to one important feature this may be accomplished by providing an opening through which air may circulate from the furnace, the opening being closed by the supplying of fuel to the furnace when the furnace is in operation.

Another object of the invention is to provide a heating system in which the flue gas is circulated from the furnace through suitable pipes or other heat extracting means in which sensible and latent heat is removed therefrom. Preferably a blower or the like is employed to circulate the flue gas which may be controlled by the supply of fuel to the furnace.

According to one important feature the air circulating opening and the blower are controlled by a pressure responsive device connected to the fuel supply and a flow restricting device is provided in the connection to prevent a rapid return of fuel from the device to the supply which might flash in the furnace.

Still another object of the invention is to provide a heating system in which the flue gas is normally circulated through a heat extractor but in which a connection to a stack or the like is opened in case of stoppage or failure of the heat extractor.

Other objects and novel features of the invention including desirable subcombinations and structural elements will be apparent from the following description when read in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a heating system embodying the invention;

Figures 2 and 3 are partial sections showing the parts in different positions;

Figure 4 is a partial section of a modified construction;

Figure 5 is a diagrammatic view of an alternative form of heating system;

Figures 6 and '7 are partial sections with parts on an enlarged scale showing different positions;

Figure 8 is an enlarged section of the resistance unit of Figure 5; and

Figure 9'is an enlarged section of the diaphragm unit ofFigu're 5;

Referring. first to Figure I there is shown a heatingsystenijcomprising a furnace Ill having a a gas burner unit I! connected to a supply pipe i4 through a control valve l6 and a pressure reducing valve I8. The valve I6 may be controlled in any desired manner as through a room thermostat to turn the fuel supply to the burner unit on and off as the demand for heat varies.

The furnace II) has an outlet pipe 20 for flue gas which is connected to a draft diverter casing 22. The casing 22 has anopen bottom, a pair of openings 24 and 26 in its top and an opening 28 in its side.

Flue gas is normally removed from the casing 22 through the opening 24 which is connected to a suitable heat extractor shown simply as an elongated piece of flue pipe 30. The pipe 30 may be of any desired length and may extend through a basement, a garage or any other desired space to be heated. Flue'gasis drawn through the pipe 30 by an electrically driven blower 32 which may discharge into a stack or through any other suitable opening to atmosphere.

The opening 28 communicates with a pipe 34 preferably leading to a stack but which may discharge to atmosphere in any other desired manner if no stack is convenient. A valve or damper 36 is provided in the opening 28 and is connected to abimetal strip 38 by a link 40. The strip 38 is mounted in the lower part of the casing 22 adjacent its open bottom and is arranged to close the valve 36 when cool and open the valve when heated.

The opening 26 is controlled by a valve or damper 42 weighted on one side so that it normally stands open.

In order to control the blower 32 and the valve 42 there is provided according to the present invention a mechanism responsive to the operation of the furnace. As shown, this mechanism comprises a split casing 44 housing a'flexible diaphragm 46 which is connected by a rod 48 to the valve 42. The casing 44 has its opposite sides connected by pipes 50 to the supply pipe l4 on opposite sides of the reducing valve l8. The reducing valve is used as a convenient restriction in the supply pipe l4 to create a differential pressure when fuel is flowing but it will when-'thefurnace is oil. At thisitime the valve- I6 is closed and pressure on the opposite sides of the reducing valve is equalized through a by-pass vent or the like therein. The diaphragm 48 is neutral and the valve 42 has opened under the influence of its unbalanced weight to move rod 48 to the right thereby opening the switch 84 so that blower 32 is stopped. If the furnace retains any latent heat air will circulate therethrough and be heated and flow out the opening 28 to heat the space around the furnace, thus utilizing heat which would ordinarily flow out the stack and be wasted.

When there is a demand for heat the valve I8 will be opened to establish a flow of gas to the burner unit I2 and the opposite sides of diaphragm 48 will be subjected to a pressure diiferential due to the pressure drop across the valve I8. At this time the diaphragm will move to the position of Figure 2 to close valve 42 and switch 54. The blower 32 will operate to draw the hot flue gas through the pipe 38, the pipe 38 being heated by the hot gas and serving to heat the space through which it passes. The pipe 38 is also heated by the latent heat of water vapor in the flue gas which is condensed in the pipe so that a substantial proportion of heat normally lost up the stack is utilized.

Normally the blower 32 withdraws flue gas from the casing 22 at the same rate at which it flows from the furnace. If the blower is running too fast air will enter the open bottom of the casing to reduce or break the draft effect on the furnace.

If the flue gas should fail to flow through the pipe 38 due, for example, to blower failure or stoppage it will back up in the casing 22 and tend to flow out the open bottom of the casing. As the hot flue gas strikes the bimetal strip 38 it will deflect to the position of Figure 3 to open the valve 38 and permit the flue gas to flow directly out the stack. Thus there is no possibility of flue gas being discharged into the space around the furnace and the only bad effect of failure of blower 32 or stoppage in pipe 38 is loss of the heat ordinarily recovered from the flue gas.

Figure 4 illustrates a slightly modified construction in which parts corresponding to like parts in Figures 1 to 3 have been indicated by the same reference numerals. In this construction the opening 28 and the stack connection are omitted and the bimetal strip 38 operates a contact arm 88 engageable with either of a pair of contacts 58 and 88. The arm 58 is connected to one side of a power circuit and the contacts 58 and 88 are connected respectively to a control circuit for the gas valve such as I8 and to an alarm circuit including an alarm shown as a bell 82.

In normal operation the strip 88 is in raised position and arm 58 springs up to engage the contact 48 so that the furnace may operate under the control of a suitable room thermostat or the like. In the event of stoppage or blower failure the hot flue gas will be directed downwardly out the bottom of the casing 22, heating the strip 38 so that it will move to the position shown in Figure 4. This moves arm 58 out of engagement with contact 48 and into engagement with contact 58 to interrupt the operating circuit and close the alarm circuit. Thus the occupants of the house or other operator will be informed that something is wrong and may remove the stoppage or repair the blower to restore normal operation.

furnace I8 having a pair of burners I2 supplied with fluid fuel such as gas from a' supply pipe I4. The gas is controlled by a combined reducing and control valve "operated by fluid pressure under the control of a valve unit II which may in turn be controlled electrically by a room thermostat or the like.

The furnace has a flue gas outlet 88 connected to a draft diverter casing 82 formed with an open bottom, a pair of openings in its top, and a side opening. The side opening is connected to a pipe 84 leading to a stack or the like and a valve 88 is provided therein controlled by a bimetal strip 88 in the same manner as the strip 38 of Figure 1 controls the valve 38. One of the top openings communicates with a heat extractor pipe 88 connected to an electrically driven blower 82 and the other top opening is provided with a valve 84 weighted so as normally to stand in open position.

The blower and the valve 84 are controlled by a diaphragm 88 in a split casing 88, one side of which is open to atmosphere through a pipe 88 and the other side of which is connected through a pipe I88 to the supply pipe 14 between the valve 18 and the burners I2. The diaphragm is connected to the valve 84 by a rod I82 which has an extension engaging and operating a control switch I84 for the blower.

Since the pipe I88 communicates with the open burners it might happen that when the furnace shuts down, gas flowing back toward the burners from the diaphragm chamber would flash or explode in the furnace. To prevent this a resistance device I88 is provided in the pipe I88 to restrict the flow of gas. As best seen in Figure 8 the device I88 comprises a body I88 formed with a through passage II8 closed against flow in the downward direction by a check valve II2. A by-pass I I4 is formed in the body and includes a threaded portion in which there is loosely threaded a plug II 8. The plug H8 is loose enough to permit gas to flow slowly past it, the degree of looseness being controllable by adjusting the plug.

When the valve I8 is opened the pipe I88 is subjected to gas pressure and gas flows up it, unseating the check valve II 2 as shown in Figure 6 and pressing the diaphragm 88 to the left to close valve 84 and switch I84. When the valve I8 is closed the pressure in the lower part of pipe I88 drops to atmospheric and gas tends to flow back from the casing 88 to the burners. At this time, however, the valve II2 closes as shown in Figure 7 and the gas must flow through the by-pass II4 past the plug II 8. Thus the gas in casing 98 is fed back slowly to the burners and the danger of flashing or exploding is minimized.

While two embodiments of the invention have been shown and described in detail it will be apparent that many changes might be made therein and it is not intended to limit the scope of the invention to the exact forms shown nor otherwise than by the terms of the appended claims.

What is claimed is:

1. In a heating system including a furnace,

, means to supply fuel to the furnace, and con- The system of Figures 5 to 9 includes a 7 trol means for the supply means, the combination of a casing connected to the furnace 'to receive flue gas therefrom and formed with a pair space to be heated by air circulating through the furnace, a valve controlling the other of said openings, and means controlled by opera-. tion of the fuel supply means to operate the valve.

2. In a heating system including a furnace, means to supply fuel to the furnace, and control means for the supply means, the combination of a casing connected to thefumace to receive flue gas therefrom and formed with a pair of openings, means connected to one of said openings to conduct flue gas away from the furnace the other opening communicating with a space to be heated by air circulating through the furnace, a normally open valve controlling the other of said openings, and means operated by supply of fuel to the furnace to close said valve.

3. In a heating system including a furnace, means to supply fuel to the furnace and control means for the supply means, the combiling the side opening, and a bimetal strip mountnation of a casing connected to the furnace to receive flue gas therefrom and formed with a pair of openings, means connected to one of said openings to conduct flue gas away from the furnace, a valve controlling the other of said openings and means controlled by operation of the fuel supply means to operate the valve, a third opening in said casing adapted to be connected to a stack, a valve controlling said third opening, and means responsive to an accumulation of flue gas in the casing due to stoppage of the means connected to said first opening to control the last named valve.

4. In a heating system including a furnace, means to supply fuel to the furnace, and control means for the supply means, the combination of a casing connected to the furnace to receive flue gas therefrom and formed with a pair of openings, means connected to one of said openings to conduct flue gas awayfrom the furnace, a valve controlling the other of said openings, and means controlled by operation of the fuel supply means to operate the valve, a third opening in said casing adapted to be connected toa stack, a valve controlling said third opening,

and thermostatic means responsive to the tema pair of openings in its top and an opening in its side adapted to be connected to a stack or the like, means connected to one of said top openings to conduct flue gas away from the furnace, a valve controlling the other of said top openings, means responsive to the supply of fuel to the furnace to control said valve, a valve controlling the side opening, and temperature responsive means in the lower part of the easing to control the last named valve.

6. In a heating system including a furnace, means to supply fuel to the furnace, and control means for the supply means, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having an opening in its top and an opening in its side adapted to be connected to a stack or the like, means connected to said top opening to conduct flue gas away from the furnace, a valve controlling the side opening, and temperature responsive means inthe lower part of the casing to control said valve.

7. In a heating system including a furnace, means to supply fuel to the furnace, and control means for the supply means, the combination of a casing connected tothe furnace to receive flue gas therefrom, said casing having an opening in its top and an opening in its side adapted to be connected to a stack or the like, means connected to said top opening to conduct flue gas away from the furnace, a valve controled in the casing and connected to said valve to control it. v

8, In a heating system including a furnace,

means to supply fuel to the furnace, and con-' trol means for the supply means, the combination of a casing connected'to the furnace to receive flue gas therefrom, said casing having an open bottom, a pair of openings in its top and an opening in its side adapted to be connected to a stack or the like, means connected to one of said top openings to conduct flue gas away from the furnace, a valve controlling the other top opening, means responsive to the flow of fuel to the furnace to control said valve, a valve controlling the side opening, and thermostatic means in the casing adjacent the open bottom thereof to control the last named valve.

9. In a heating system including a furnace,

means to supply fuel to the furnace, and concontrolling the other of said openings, means responsive to the supply of fuel to the furnace to control said valve, and control means for the gas circulating means operated by said last named 7 means; a

10. In a heating system including a furnace, means to supply fuel to the furnace, and control means for the supply means, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having a pair of outlet openings therein, an electrically operated blower connected to one of said openings to withdraw flue gas from the casing the other opening communicating with a space to be heated by air circulating through the furnace,

a valve controlling the other of said openings, means responsive to the supply of fuel to the furnace to control said valve, and a switch for controlling said blower operated by said last named means.

11. In a heating system including a furnace, a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having a pair of outlet openings therein, gas circulating means connected to one of said openingsto withdraw flue gas from the casing the otheropening communicating with a space to be heated by air circulating through the furnace, a valve controlling the other of said openings, and a fluid operated device connected to the supply pipe and to said valve to operate the valve in response to the supply of fluid fuel to the furnace.

12. In a heating system including a furnace,

a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom, said cas ing having a pair of outlet openings therein, gas circulating means connected to one of said openings to withdraw flue gas from the casing the other opening communicating with a space to be heated byair circulating through the furnace, a norfnally closed valve controlling the other of said openings, and a fluid pressure responsive device connected to said valve and to the supply pipe to closesaid valve in response to pressure created by the fuel.

13. In a heating system including a furnace, a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having a pair of outlet openings therein, an electrically operated blower connected to one of said openings to withdraw flue gas from the casing the other opening communicating with a space to be heated by air circulating through the furnace, a valve controlling the other of said openings, and a fluid operated device connected to the supply pipeto be actuated by the fuel pressure therein, and connected to said valve to operate it, and a control switch for the blower operated by said device.

14. In a heating system including a furnace, a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having a pair of outlet openings therein, gas circulating means connected to one of said openings to withdraw flue gas from the casing the other opening communicating with a space to be heated by air circulating through the furnace, a valve controlling the other of said openings, and means responsive to the flow of fluid through the supply pipe to operate the valve.

15. In a heating system including a furnace, a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having a pair of outlet openings therein, gas circulating means connected to one of said openings to withdraw flue gas from the casing the other opening communicating with a space to be heated by air circulating through the furnace, a valve controlling the other of said openings, and means responsive to the pressure of fuel in the supply pipe posterior to the control valve to operate the last named valve.

16. In a heating system including a furnace, a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom. said casing having a pair of outlet openings therein, gas circulating means connected to one of said openings to withdraw flue gas from the casing, a valve controlling the other of said openings, means connected to the supply pipe and responsive to the pressure of fuel therein to operate said valve, and a flow restricting device between said last named means and the supply pipe to restrict the flow from the last named means to the supply pipe, said device including a by-pass controlled by a check valve to permit substantially unrestricted flow from the supply pipe to the last named means.

17. In a heating system including a furnace, a supply pipe for conducting fluid fuel to the furnace, and a control valve in the supply pipe, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing having a pair of outlet openings therein, gas circulating means connected to one of said openings to withdraw flue gas from the casing, a valve controlling the other of said openings, a fluid pressure operated device to control said valve, a connection from the supply pipe posterior to the control valve to said device to actuate it and flow restricting means insaid connection to restrict return flow of fuel from the device to the supply pipe, said restricting means having a by-pass controlled by a check valve to provide for substantially unrestricted flow of fuel from the supply pipe to the device.

18. In a heating system including a furnace, means to supply fuel to the furnace, and control means for the supply means, the combination of a casing connected to the furnace to receive flue gas therefrom, said casing being formed with a pair of outlet openings therein, one of which is adapted to be connected with a stack, valves in said openings, means responsive to the flow of flue gas through the casing to control the valve in said one opening, and means responsive to supply of fuel to the furnace to control the valve in the other of said openings, said last-named opening communicating with a space to be heated by air circulating through the furnace.

FRANCIS A. FURLONG. 

